Circuit breaking mechanism



June 16, 1942. L, H, COTT 2,286,235

IIIIIIIIIIIIIIIIIIIIII SM Z1050 H Sal/z June 16, 1942. sco 2,286,235

CIRCUIT BREAKING MECHANISM Filed July 31, 1941 5 Sheets-Sheet 2 INVENTOR TTORNEY June 16, 1942. L. H. SCOTT 2,286,235

CIRCUIT BREAKING MECHANISM Filed July 51, 1941 Sheets-Sheet 3 NVENTOR ATTORNEY June 16, 1942. L, H; COTT 2,286,235

CIRCUIT BREAKING MECHANISM Filed July 31, 1941 5 Sheets-Sheet 4 i5 riiiimuwnwa a"" 16 y" wi liihli bl L1,; 4%

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IN VENT OR.

Llayd 1/. sm/z ATTORNEYS June 16, 1942. H -r 2,286,235

CIRCUIT BREAKING MECHANISM Filed July 31, 1941 Sheet s-Sh eet 5 INVENTOR.

TORNEYS Patented June 16, 1942 OFFICE ciacurr BREAKING MECHANISM Lloyd B. Scott, Garden City, N. Y., assignor to The Seymour Corporation of Delaware, Seymour, Conn., a corporation oi Delaware Application July 31, 1941, Serial No. 404,820

18 Claims.

This invention relates to circuit breaking mechanisms, and more particularly to a make-andbreak device adapted to impart a desired timing characteristic to an intermittent current in electrical apparatus, such as in an ignition system for an internal combustion engine.

The invention has for its object generally an improved construction for circuit breaking mechanisms of the character indicated which is rugged, relatively foolproof, and readily adapted to be constructed to give a desired timing characteristic and number of sparks.

More particularly, the invention has for its object the provision of a make-and-break device for use in ignition systems or the like, which is positively actuatedby a rotating part to give a desired number of sparks with each revolution, and is symmetrically constructed so as to be installed to be used with either direction of rotation of the actuating rotating part.

Another object is to provide a breaker mechanism applicable to magnetos intended for use on r'nulti-cylinder internal combustion engines of the type used in aviation whereby the breaker device may be operated at an extremely rapid rate, in a manner positively providing makes and breaks with proper timing at all speeds and without the use of heavy spring loading heretofore employed and considered necessary.

Another object is to provide a breaker mechanism that may be run continuously and reliably at higher speeds than was heretofore permissible, the breaker mechanism effecting a desired number of makes and breaks for each revolution at all times during the entire speed range.

Another object is to provide a breaker actuating cam for moving a breaker arm structure positively in both directions and which is doubleacting, so as to dispense'with the use of spring loading devices.

Still another object is to provide a contact mounting in a circuit breaking mechanism of a character such that two or more contacts may be mounted for actuation and individually adjusted to give a desired action.

A still further object of the invention is the provision of such circuit breaking mechanism wherein a breaker arm has one end thereof mounted on mounting means for oscillatory movement about a point fixed relative to said mounting means and a cam follower at the other end thereof with rotating cam means for imparting movement positively in two opposite directions to the camfollo'wer, the breaker arm struccontact means adapted when the breaker arm structure is oscillated to make-and-break with a contact mounted on the mounting means.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplified in the construction hereinafter set forth and the scope of which invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

Fig. 1 is a front elevational view showing a breaker mechanism embodying the invention,

mounted on a stationary member which may be the end wall of a casing or housing;

Fig. 2 is a view, partly in section and partly in side elevation showing details of such breaker mechanism including its actuating cam;

Figs. 2 and 2 are fragmentary views showing modified forms of actuating cams:

Fig. 3 is a sectional view, taken on the line 33 in Fig. 2;

Fig. 4 is a view showing a development of the cam employed in Figs. 1 and 2;

Fig. 5 is a schematic tviring diagram;

Fig. 6 is a plan view of a modified form of breaker mechanism of the present invention adapted to be mounted in a manner similar to the structure shown in Figs. 1 and 2 and to be operated by similar cam means;

Fig. 7 is an elevational view of the structure shown in Fig. 6;

Fig. 8 is a sectional view taken on line 8-4 of Fig. 6;

Fig. 9 is a sectional view taken on line 9-9 of Fig. 8;

Fig. 10 is a view similar to Fig. 6 of still another modification of the present invention;

Fig. 11 is a sectional view taken on line ll--|| of Fig. 10;

Fig. 12 is a sectional view taken on line 12-" of Fig. 10; I

Fig. 13 is a view similar to Figs. 6 and 10 of a still further modified form of breaker mechanism of the present invention;

Fig. 14 is an elevational view of the structure shown in Fig. 13;

Fig. 15 is a view similar to that of Figs. 6, l0

ture being provided intermediate its ends with and 13, but with parts broken away, of an additionai modification of breaker mechanism of the present invention; and

Fig. 16 is an elevational view of structure shown in Fig. 15.

In make-and-break devices for electrical circuits which are intended to make a desired number of makes and breaks for each revolution of a.

employed to move the arm in the other direction.

Difiiculties have been experienced with such breaker devices when they are operated at high speeds; and since the speed with which the breaker arm can be moved by the spring is dependent upon the inertia of the breaker arm and the pressure exerted by the spring, efforts have.

been made to overcome these difiiculties by reducing the weight of thebreaker arm and increasing the loading of the spring. Such expedients however, while serving to increase somewhat the speed at which the breaker device can be operated, have introduced or accentuated other difliculties suchas excessive hammering of the contacts in operation with increased rate of destructive wear, and chattering or bouncing of the contacts. The best of such breaker devices presently available seem inherently incapable of satisfactory operation at the high speeds which are presently desirable, and have limited the development of the. art.

By the present invention a breaker device is achieved in which a contact is mounted for oscillatory movement by a breaker arm structure which .is positively actuated first in one direction and then in the opposite'direction by a rotating cam. By this arrangement the inertia of that portion of the device carrying the movable contact is rendered practically a negligible factor even in operation at high speed, and the pressure exerted by the movable contact on the sta tionary contact can be adjusted to that which is most desirable for the electrical functioning of the device without the necessity for taking into account its effect on the mechanical operation of the device,and the optimum contact pressure can be maintained substantially uniform throughout the entire range from low to very high speed.

' Furthermore, since the breaker arm structure is positively cam actuated in both directions a pair of such movable contacts oscillated thereby can be made to cooperate with two stationary contacts, thereby doubling the number of makes and breaks which can be obtained with a given number of vibrations or oscillations of the breaker arm structure.

In accordance with the present invention, a make-and-break device is provided with a breaker arm structure having one end thereof mounted for oscillatory movement about a fixed point and the other end thereof provided with a cam follower to be actuated by an actuating cam in both directions in order to dispense entirely with the usual springs. This breaker arm structure is provided intermediate its ends with the movable contact member. Such breaker arm structure may be actuated by a cam directly on the rotor shaft that is connected to be driven by the airplane engine and can be made relatively small and mounted at a convenient point in a magneto assembly, for example, on a casing wall of the magneto.

Referring now to the drawings, and particularly to Fig. 1, III denotes a stationary member, such as a circular end wall of a magneto casing, from which member projects a mounting member II, the latter being shown as disposed substantially on a radius of the end wall; the mounting member preferably having parallel mounting surfaces, for reasons hereinafter explained. The breaker proper comprises a portion or base I2 which is secured to member II; such portion having an insulating facing, as shown at I2, and an interposed spacing member or members as shown at I2", when desired. Base I2 is arranged to support one or more side plates in an insulated manner, such side plates being shown at I3 and I3 on facing I2, each side plate carrying a contact, as shown respectively at I4 and I4. Base I! also carries a resilient breaker arm or blade I5 of electrical conducting metallic material which is mounted to be positively actuated in both directions, and dispenses with spring loading; the mounting being such that blade I5 may carry contacts for engagement with contacts I4 and I4. To this end, blade I5 is attached by a post or column I6 to base I2 in a manner permitting vibratory movement. The other end of blade .I5 is here terminated in a bob I9, which may be conical, ball-shaped or cylindrical, and is adapted to serve as a follower for actuation by a cam surface of a cam 20.

The blade I5, as more fully shown in Figs. 2 and 3, is seen to have mounted on opposite sides thereof at suitable points intermediate the ends thereof, contact members I5I and I52 which are adapted to engage with the contacts I4 and I4. In order that the engagement of contactsI4 and I4 by contact members I5I and I52 may be at desired instants of time in the path of their movement on either side of the mean or neutral position of blade I5, the contacts I4 and I4 are preferably made relatively adjustable. To this end, the side plates I3 and I3, which are provided with upstanding lugs I3I and I32 for carrying the contacts I4 and I4, are pivotally attached to the base I2 so as to be moved'relatively to the blade I5 in the plane of the base I2. Screws at I33 and I33 are hence provided and arranged to serve not merely as securing means for side plates I3 and I3 respectively but also as the pivot points about which the plates swing. Additional screws I34 and I34 are also provided for each side plate which serve as securing and locking means, the openings in the side plates through which these screws pass being elongated along the circumferences of circles drawn about the pivot points as centers. By this arrangement, limited lateral movement of the side plates is permitted. .The side plates I3 and I3 are each overlaid by a top plate through which screws I33, I33, I34 and I34 extend as shown in Fig, 3. To achieve close adjustment in the movement of the side plates, screws I35 and I35, which have eccentric, or cam-like disks on their shanks, are passed through or rotatably mounted in apertures in top plates I8 and I8 overlying the side plates, I3 and I3 with the cam-like disks or heads thereof engaged in elongated slots in the side plates, these elongated slots having their major axes preferably disposed to lie along radii of circumferences drawn about the pivot points. In this way, a tool engaging with the kerf in screws I35 and I35 may be employed to adjust the contacts I4 and I4 relatively to the blade I5 by substantially any desired lateral displacement.

It is believed to be obvious that top plates l8 and It may be omitted if the shanks of adjusting eccentrics I 35 and I35 are rotatably mounted in holes in side plates l3 and I3 and their cam-like heads engaged in such elongated slots in structure lying therebeneath, such as the insulating member l2. Since the latter is fixed,

rotation of the shanks of eccentrics I35 and I35 in the side plates 13 and I3 will cause the latter to be pivoted about screws I33 and I33.

In the practice of the invention, the blade I5 and the contacts I4 and I4 are insulated from each other; the associated electric circuit preferably including a grounded portion. To this end, it is advantageous to ground the blade I! which is conveniently accomplished by mounting the blade IE to have its upper end in conducting relation with base I2. In the arrangement shown, the blade I! is continuous and flexible and extends from the column it down to the follower IS. The insulation l2 insulates the side plates l3 and I3 and the contacts I4 and H from base l2. Screws I33 and I, which hold the top plates II and I3 and side plates l3 and I3 in place, are provided with insulating bushings, as shown at 8|.

The actuating cam may have many forms embodying the double-acting feature. Three forms are here shown. A preferred form is shown at in Fig. 2; alternate forms being shown at 20a and 20b in Figs. 2" and 2 respectively. Cam

20 is cylindrical in form and has its geometrical axis arranged as the axis of rotation, the

cam surface being formed by cutting a groove therein. Such groove may, with advantage, be cut into the cylindrical surface and is here shown at 2|. In the circuits of ignition systems, it is desirable to have the circuit made and broken in a continuous sequence of events having substantially equal periods of time therebetween. The groove 2| is hence illustrated as a continuous sinuous path about the periphery of the cam. The development of the groove in cam 20 is shown in Fig. 4, in which the pitch-line P is a sine curve. It will be understood, however, that this is merely illustrative of one form of groove that may be employed; ,there being many others giving different timing effects that may also be employed.

Where a cam oi the type shown at 20a is employed, substantially the same eifect may be had from agroove as shown at 2. Here the base line is a circle and the sinusoidal pitch-line is laid out about the same. In the form shown in Fig. 2 the cam surface is had from a rib on the cam disk, disposed about its periphery. Such rib may have a sinuous pitch-line, as in the case of cam 20, but the cooperating follower on the breaker arm is required to be of a form different from that at I9, for example, a follower in fork-form, as shown at l5, following both sides of the rib.

The actuating cam is on a driven shaft 22 whichis mechanically coupled to a master rotating element, such as the shaft of the rotor of a magneto-electric machine that is driven by the engine for which ignition is to be supplied. Shaft 22 is accordingly shown as journaled in the casing wall In by suitable bearing means, such as antifriction bearings 23.

electric circuit such as that of a magneto in ignilion service for internal combustion engines. An

exemplary circuit utilizing such breaker mechanism in this manner is shown in Fig. 5, where the blade i 5 is seen to engage alternately with contacts I4 and N that are in a circuit comprising a conductor 24 which is connected to a terminal of a primary winding 2 and an associated secondary 252; the two windings having a common ground at one end as shown at 23. The primary is of course inductively related to the magnetic circuits of the rotor and stator above described, whereby a primary EMF is induced when the rotor is rotated. The blade I5 is seen to have its support at It also grounded. Hence, a condenser is preferably connected around contacts I and I4 through ground. To this end, a condenser 28 is provided which has one terminal connected to conductor 24 and the other to ground. Such condenser is conveniently mounted on casing wall Hi and is shown secured by a bracket 29. A grounding switch 30 may also be conveniently included in the circuit which is effected by attaching .it to one end of conductor 24, the other side being grounded. The other terminal of the secondary 252 is led to a spark gap which may be that in the cylinder of an engine to be fired by the circuit shown.

In the arrangement of the present invention, it is preferable that the direction of rotation of the cam, such as that at 20, be one which puts a drag on the blade so that it may be under tension rather than under compression. In Fig. 1, the breaker mechanism is illustrated as mounted on the left side of the member II. The cam, in consequence, should be rotated counterclockwise.

It is advantageous, although by no means necessary, to arrange the parts in a symmetrical manner, in order that the parts may be reversed in order to effect a clockwise rotation of the cam, for a different connection to the driving engine. The breaker mechanism for such purpose is mounted on the right side of the member II. This, of course, is readily accomplished, since all that is needed to be done is to remove the breaker from the left side of the member II and then mount it on the right side. The symmetry of the mounting member II with respect to the cam permits this, the member H being shown as bounded by planes that are parallel to the axis of the cam shaft 22,

While, in providing such symmetry, it is convenient to arrange member i i so as to lie on such cam disk radius, such arrangement is not necessary, as member Il may be given other shapes and still be symmetrical and preserve the fea- .ture 'of interchangeability for mounting the breaker; for example, the member H may be triangular in shape, the altitude of the triangle coinciding substantially with the radius of the disk 20 extended. In this latter case, the follower would advantageously be spherical. Also, it will be seen that the mechanism of the invention is such that two or more breakers proper may be mounted at one time on the stationary member I.

In the arrangement shown in Figs. 1 to 4, inclusive, which has contacts on each side of the breaker arm adapted to be contacted alternately when the arm is vibrated or oscillated, there is structural symmetry about the neutral line of blade [5, but this symmetry is also not essential, nor the use of two contacts, sinc an operative symmetry may be accomplished by providing merely one live contact, the place for the other being occupied by a so-called "dummy or by no contact at all.

The present mechani m is seen also to be readily adapted for make-and-break service at high speeds. The inertia of the vibrating arm has little effect on the operation of th device except as to the pressure betwen the cam and cam follower required to overcome the inertia. The moving part or vibrating arm may be relatively thin, thereby reducing the mass and inperiods in which the arm is intended to oscillate.

when in operation, even at high speeds. A breaker arm, positively actuated in both directions and devoid of spring loading, is thus seen to be here provided, which is free from complications due to the introduction of unwanted harmonics.

Blade l as described above is flexible and made fast in column I6 in any suitable manner, for example, by forming a slot in the top of the column for receiving the blade. While thi is advantageous, it may obviously have an articulated portion that is to be gripped by'the sides Limited pivotal movement of side plates I3 and I3 is permitted by transverse slots (indicated vby dotted lines in Fig. 6) through which are engaged locking screws I34 and I34. Each of these side plates I3 and I3 is provided with a longitudinal slot 36 in which is located the shank of an eccentric member I35 or l.35'. shank of the eccentric member is provided a cam'like disk or head 31 rotatably mounted in a socket in the land 35 so that as this eccentric member is rotated by a tool when the locking member I34 is loosened the side plate will be pivoted around its pivot point screw I33 for limited lateral adjustment of the fixed contact I4.

The breaker arm structure referred to generally by numeral I5 includes a main breaker arm 33 having a flexible section 39 adjacent the mounting end thereof which is mounted with a.

pair of auxiliary breaker arms 40, 40 with interposed spacing members I'I, I1 between the posts I6, I6. The major portion of the breaker arm is relatively rigid which is attained by the provision of opposed webs 4|, M on the upper edge thereof which extend from the flexible section to and preferably integral with the cam follower I9.

of column I6 or it may be pivoted to its support. The thin blade, however, has inherently a flexibility which may be utilized to insure that good contact is made between the contacts l4 and I4 and the contact members on the blade. The amplitude of oscillation of the arm or blade I5 is, of course, determined by the amplitude of the pitch-line P of th cam groove zl. Thus, when the breaker is initially mounted on the member II, the side,plates, which carry the con tacts, are preferably adjusted to have the contacts engaged by the contact members on the blade I5 a little in advance of the instant when the arm reaches a maximum point in its path of swing. Thus, the final movement of the blade I5 results in a slight fiexure thereof, accompanied by the imposition of pressure on the contact members when in engagement with the contacts either at I4 or I4. Such pressure is seen to be advantageous in insuring good contact, as well as determining the period of time for which the contacts engage.

In the modified form shown in Figs. 6 to 9.

inclusive, the breaker base l2 of metallic conducting material is secured to the mounting member or bracket II by means of screws 2525 as in the first modification. The breaker arm structure I5 comprising a blade is mounted upon the breaker base I2 by means of a pair of spaced apart uprights or posts I6, preferably integral with the base, and by means of transve se screws 26, 26 and a nut plate 21.

As in the first modification a plate or block of insulating .material I2I is mounted upon the breaker base I2. In any suitable manner such as by a dowel pin 32 and screws 3333. preferably three, one of which is shown in Fig. 8.

insulating block I2I is provided with a longitudinal groove 34 defining spaced apart lands 35, 35 to support the side plates I3 and I3 which respectively carry the fixed contacts I4 and I4. The side plates I3 and I3 are pivotallymounted on lands 35, 35 by screws I33 and I33 which are and ,a pair of webs 42, 42 on the lower edge thereof preferably extending from the flexible section 39 for a considerable distance but short of the follower I9. The omission of the latter stiffening. webs 42, 42 adjacent the follower I9 is for the purpose of preventing interference with operation of the cam.

As shown the auxiliary arms 40, 40, each carrying on the end thereof one of the two movable contacts I5I and I52, preferably extend for a major portion of their length substantially parallel to and slightly spaced from the main breaker arm 38, while being positioned intermediate webs M and 42. Between the ends of each auxiliary breaker arm 40 a portion 43 is bent or gradually curved outwardly to carry the movable contact spaced an appreciable distance from the-main breaker arm 38 as shown in Figs. 6 and 9. This spacing permits a fair amount of movement of theauxiliary .breaker arm 40 relative to main breaker arm 38 during operation to secure positive and secure seating of the movable contact with the fixed contact during a predetermined period of make.

Movement of the auxiliary breaker arms 40, 40 away from the main breaker arm 38 is limited by a clip member 44 preferably in the form of a rectangular loop as shown fixed to the main breaker arm 38 and including side portions 45, 45 to serve as travel limiting means for the auxiliary breaker arms. This clip member 44 may be mounted in position by slipping it over the end of the breaker arm 38'which is to be fixedly supported priorto mounting the latter on the support. This clip member 44 is for the purpose of drawing the auxiliary breaker arms 40, 40 in toward the main breaker arm 38 and to hold them under tension in the position shown, and further for the purpose of avoiding impositive operation which might occur through inertia of the auxiliary breaker arm and the movable contacts carried thereby during rapid oscillation of Upon the aasaaso I farther radially from the axis of rotation of the functions.

In the modification shown in Fig. 10 a breaker base II2 of metallic conducting material preferably is mounted upon a mounting member or bracket III and is preferably provided with a pair oi spaced apart posts I0, I5 preferably made integral with the breaker base 2. A breaker arm structure I5 is mounted between the posts I5, I6 by means similar to those described above in connection with Figs. 6 to 9, incl. A flexible main breaker arm I" is mounted between the pair of posts I6, I and carries at its other end a cam follower II9. Spacer members- I1, II are provided laterally to space from the main breaker arm I58 a pair of resilient auxiliary breaker arms I40, I40 which carry the movable contact members II and I52. Portions 40, 45 at the free ends of the breaker arms I40, I40 beyond the contacts III and I52 are both received in a slot 41 of substantial width to provide for a substantial amount of but limited transverse movement.

On the breaker base H2 is mounted an insulating block 22I by any suitable means such as screws, 40 and 40 and the face of this block is curved to accommodate a cam 20 so that the latter may be brought up closer to the breaker base II2 thereby avoiding the necessity of using a relatively long breaker arm structure. The insulating block 22I is provided with a longitudinal groove 50 of substantial width to assure freedom of action of resilient breaker arm I55 which is mounted therein. As a result of such foreshortened structure it will be seen that with the cam follower II! mounted over the vertical radius of the cam 20 a considerable portion of the main breaker arm ill will ride along with the cam follower H9 in the sinusoidal groove 2i of the cam 20. Accordingly, -to avoid interference with operation of the cam 20 by auxiliary breaker arms I40, I40 and the contacts I52, I52 mounted thereon, the auxiliary breaker arms are preferably mounted beyond .the main breaker arm I38, that is, outwardly of the cylindrical surface of the cam 20 as shown in Fig. 11.

The auxiliary breaker arms I40, I40 are caused to operate with the main breaker arm I40 by having their ends engaged in the slot 41 in the cam follower IIS, this slot permitting limited transverse action of the auxiliary breaker arms relative to the main breaker arm for assuring positive and secure seating of the movable contacts I5I and I52 with the fixed contacts I4 and I4 during a predetermined period. The follower II! and the slot 41 therein in this instance function similarly to the clip 44 in the modification shown in Figs. 6 to 9, incl.

In the modification shown in Figs. 13 and 14 the breaker base, supporting bracket, insulating block, side plates and associated structure are similar to those of the modification shown in Figs. 6 to 9, incl., and bear like reference numerals. The breaker arm structure, however, is somewhat similar to that disclosed in Figs. 10, 11 and 12 with the exception that the auxiliary arms I40, I40 are positioned substantially alon the sides of the main breaker arm I38 rather than being located at a different level or, that is,

cam. This is permitted by the use of a cam follower 2I0 whichlike the other cam followers is substantially cylindrical but in this case has its axis. referenced X, disposed at an angle of about 45 to a cam radial, referenced Y, which is subbase I2 and bracket II.

stantially parallel to the faces of the breaker As a consequence although the movable contact I 5i and I52 are carried near the endsof the auxiliary breaker arms I40, I40 these will be located beyond the cylindrical surface of the cam 20 as own in Fig. 14. The operation of this modification is similar to the operation of that disclosed in Figs. 10, 11 and 12.

In Figs. 15 and 16 a further modified form is shown wherein the breaker arm structure is in the form of a single breaker arm 5| having a fiexible portion I39 adjacent the fixed end thereof and the major portion thereof made substantially rigid by a pair of opposed ribs 52, 52 which are preferably of greatest depth adjacent the location of the movable contacts I5I and I52 and which continue at least adjacent to the cam follower IQ. Since it is desired to assure secure seating of the movable contacts with respect to the fixed" contacts during predetermined periods while avoiding chattering, provision is made for resiliently mounting the so-called fixed" contacts on the supporting structure. This is preferably accomplished by providing slots in the ends of the sideplates I I and I5 to receive the ends of short resilient arms 53 which are riveted in position therein as shown in Fig. 15. On each side plate is provided an extending portion 54 having the major portion thereof spaced inwardly from the resilient arm 53 and terminating in a nose 55 extending to engagement with a face of resilient arm 53. Accordingly, as the breaker arm 5I is moved laterally by the cam a movable contact thereon such as I5I engages the cooperating contact I4 and then upon further lateral movement in the same direction the flexible arm 53 is flexed outwardly away from the nose 55 until as the breaker arm 5I is returned toward the medial position the nose 55 engages the flexible breaker arm 53 to cause the operating contacts positively and quickly to separate. The resiliency of the arm 53 is thus seen to assure positive and secure contact between cooperating contacts during the period of make.

In operation, when shaft 22 is rotating, the cam, such as that at 20, causes the follower, such as that at I9, to vibrate or oscillate the breaker arm structure; the number of vibrations or oscillations per revolution of the shaft desired determining the shape of the groove 2i. it is seen that the number of makes and breaks effected by the breaker mechanism of the present invention is directly proportional to the rate of rotation of shaft 22, regardless of speed.

The present application is a continuation-inpart of my prior application Serial No. 350,533 filed August 3, 1940.

Since certain changes may be made in the above construction and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described my invention; what I claim Hence,

as new and desire to secure by Letters Patent,

1. In a circuit breaking mechanism, the combination with a rotating member, of a stationary support, a breaker arm structure mounted at one end on said support for oscillatory movement and provided at its opposite end with a cam follower, and a cam on said rotating member having means for imparting movement positively in two opposite directions to said cam follower, said breaker arm structure being provided intermediate its ends with a contact member argated breaker arm, structure having one end thereof mounted on said means for oscillatory movement about a point fixed relative to said mounting means, a cam follower at the other end of said breaker arm structure engaging said cam track for continuous contact therewith, a

contact member mounted on a portion of said breaker arm structure which is intermediate its ends, and a second contact member mounted in fixed position relative to said mounting means to make and break with said breaker arm structure contact member when said breaker arm structure is oscillated by said cam.

.3. In a circuit breaking mechanism, the combination with a rotating member, of a breaker arm structure provided intermediate its ends with a contact member and having a cam follower adjacent one end, means for mounting said breaker arm structure for oscillatory movement about a fixed point at the end remote from said follower, a cam on said rotating member having means for positively imparting movement in two opposite directions to said cam follower, and a stationary contact arranged to be engaged by said contact member when said breaker arm structure is actuated by said cam; the direction of rotation of said cam being such as to apply tension to said breaker arm structure.

4. In a circuit breaking mechanism, the com-- bination with a'rotating member, of a cylindrical cam on said rotating member with its geometrical aixs coincident with the axis of rotation and formed with means for imparting move ment positively in two opposite directions, a flexible breaker arm structure provided with an intermediately disposed contact member and with a cam follower adjacent one end. means for rigidly supporting said breaker arm structure for receiving oscillating impulses in both directions and at the end remote from said follower and in a position such that said follower engages with said cam. a contact on said supporting means arranged for engagement by said contact member when said breaker arm structure is oscillated, and means for insulatingly supporting said contact with respect to said breaker arm structure.

5. In a circuit breaking mechanism, the combination with a rotating member. of a cylindrical cam on said rotating member with its geometrical axis coincident with the axis of rotation and formed with means for positively imparting movement in two opposite directions, a flexible breaker arm structure provided with an intermediately disposed contact member and with a cam follower adjacent one end, mounting means stationary with respect to said rotating member, a supporting plate secured to said mounting means, said plate'having an element for rigidly and conductively supporting said breaker arm structure at the end remote from said follower and in a position such that said follower engages with said cam, a contact carried by said plate p itioned to be engaged by said intermediately located contact member when said breaker arm structure is oscillated, and means for insulatingly supporting said contact with respect to said supporting plate.

6. In a circuit breaking mechanism, the com- I bination with a rotating member, of a cylindrical cam on said rotating member with its geometrical axis coincident with the axis of rotation and formed with a means for positively imparting movement in two opposite directions, a flexible breaker arm structure provided with an intermediately disposed contact member and with a. cam follower adjacent one end, mounting means stationary with respectto said rotating member, said mounting means having supporting surfaces whose planes are substantially parallel to the axis of rotation, a supporting plate secured on a surface of'said mounting means, said plate having an element for rigidly and conductively supporting said breaker arm structure at the end remote from said follower and in a position such that said follower engages with said cam, a contact carried by said plate positioned to be engaged by said intermediately located contact member when said breaker arm structure is oscillated, and means for insulatingly supporting said contact with respect to said supporting plate.

'7. In a circuit breaking mechanism, the combination with a rotating member, of a cylindrical cam on said rotating member with its geometrical axis coincident with the axis of rotation and formed with ,means for positively imparting movement in two opposite directions, a flexible breaker arm structure provided with an intermediately disposed contact member and with a cam follower adjacent one end, mounting means stationary with respect to said rotating member, said mounting means having supporting surfaces whose planes are substantially parallel to the axis 4 of rotation, a supporting plate secured on a supporting surface of said mounting means, said plate having an element for rigidly and cond l1c.

mounted on said supporting plate, and a contact carried by said side plate positioned to be engaged by said intermediately located contact member when said breaker arm structure is oscillated.

8; In a circuit breaking mechanism, the combination with a rotating member, of a cylindrical cam on said rotating member with its geometric -axis coincident with theaxis of rotation and formed with cam track means for positively im parting movement in two opposite directions, a

flexible blade provided with a pair of contact members mounted at an intermediate point respectively on opposite sides and with a cam follower at one end for engaging said cam track means, means for rigidly supporting said blade at its other end and in a position such that said follower engages with said cam, and a pair of contacts on said supporting means arranged to be engaged respectively by said contact members when said blade is oscillated.

9. In a circuit breaking mechanism, the combination with a rotating member, of a cylindrical cam on said rotating member with its geometric axis coincident with the axis of rotation and formed with cam track means for positively imparting movement in two opposite directions, a flexible blade provided with a pair of contact members mounted at an intermediate point respectively on opposite sides and with a cam follower at one end, mounting means stationary with respect to said rotating member, said mount ing means having supporting faces whose planes are substantially parallel to the axis of rotation, a supporting plate secured on a supporting surface of said mounting means, said supporting plate having an element for holding said blade at its other end in a rigid manner and in a position such that said follower engages with said cam, and a pair of contacts on said supporting plate positioned to be engaged respectively by said contact members when said blade is oscillated.

10. In a circuit breaking mechanism, the combination with a rotating member, of a stationary support, a substantially rigid main breaker arm having a flexible portion at one end mounted on said support for oscillatory movement of said arm and provided at its opposite end with a cam follower, and a cam on said rotating member having means for imparting movement positively in two opposite directions to said cam follower, said breaker am being provided intermediate its ends with a contact member arranged to engage with and disengage from a contact mounted on said support when said breaker arm is oscillated.

11. In a circuit breaking mechanism, the combination with a rotating member, of a stationary support, a substantially rigid main breaker arm having a flexible portion at one end mounted on said support for oscillatory movement of said arm and provided at its opposite end with a cam follower, a cam on said rotating member having means for imparting movement positively in two opposite directions to said cam follower, and an auxiliary breaker arm mounted at one end on said support extending adjacent to said main breaker arm for oscillatory operation thereby and carrying a contact member intermediate the ends of said main breaker arm arranged to engage with and disengage from a contact mounted on said support when said main breaker arm is oscillated;

12. In a circuit breaking mechanism, the combination with a rotating member, of a stationary support, a substantially rigid main breaker arm having longitudinally extending spaced apart stiffening ribs providing achannel therebetween and a flexible portion at one end mounted on said support for oscillatory movement of said arm, a cam follower provided on the opposite end of said main breaker arm, a cam on said rotating member having means for imparting movement positively in two opposite directions to said cam follower, and an auxiliary breaker arm mounted at one end on said support alongside said main breaker arm for oscillatory operation thereby and disposed in said channel with a portion of said auxiliary breaker arm intermediate the ends of said main breaker arm spaced from the latter,

and a contact member mounted on said spaced portion of said auxiliary arm arranged to engage with and disengage from a contact mounted on said support when said main breaker arm is oscillated.

13. In a circuit breaking mechanism, the combination witha rotating member, of a stationary support, a substantially rigid main breaker arm having longitudinally extending spaced apart stiffening ribs providing a channel therebetween and a flexible portion at one end mounted on said support for oscillatory movement of said arm, a cam follower provided on the opposite'end of said main breaker arm, a cam on saidrotating memher having means for imparting. movement positively in two opposite directions to said cam follower, an auxiliary breaker arm mounted at one end on said support alongside said main breaker arm for oscillatory operation thereby and disposed in said channel with a portion of said auxiliary breaker arm intermediate the ends of said main breaker arm spaced from the latter. and a contact member mounted on said spaced portion of said auxiliary arm arranged to engage with and disengage from a .contact mounted on said support when said main breaker arm is oscillated and means to limit outward movement of said auxiliary arm relative to said main breaker arm.

14. In a circuit breaking mechanism, the combination with a rotating member, of a stationary support, a main breaker arm mounted at one end on said support for oscillatory movement and provided at its opposite end with a cam follower, a cam on said rotating member having means for imparting movement positively in two opposite directions to said cam follower, an auxiliary breaker arm mounted at one end on said support extending adjacent to said main breaker arm and having its other end engaging said cam follower, and a contact member mounted on said auxiliary breaker arm intermediate the ends thereof and arranged to engage with and disengage from a contact mounted on said support when the resultant breaker arm structure is oscillated.

15. In a circuit breaking mechanism, the combination with a rotating member, of a stationary support, a main breaker arm mounted at one end on said support for oscillatory movement and provided at its opposite end with a cam follower, a cam on said rotating member having means for imparting movement positively in two opposite directions to said cam follower, and an auxiliary breaker arm mounted at one end on said support extending adjacent to said main breaker arm and having its other end engaged between spaced apart transverse movement-permitting means on said main breaker arm, and a contact member mounted on said auxiliary breaker arm intermediate the ends thereof and arranged to engage with and disengage from a contact mounted on said support when the resultant breaker arm structure is oscillated 16. In a circuit breaking mechanism,'the combination with a rotating member, of a stationary support, a main breaker arm mounted at one end on said support for oscillatory movement and provided at its opposite end with a cam follower, a cam on said rotating member having means for imparting movement positively in two opposite directions to said cam follower, and a resilient auxiliary breaker arm mounted at one end on said support extending adjacent to said main breaker arm and having its other end engaged between spaced apart transverse movement-permitting means on said cam follower, and a contact member mounted on said auxiliary breaker arm intermediate the ends thereof and arranged to engage with and disengage from a contact mounted on said support when the resultant breaker arm structure is oscillated.

17. In a circuit breaking mechanism, the combination with a rotating member, of a station- 4 ary support, a main breaker arm mounted at one cnd on said support for oscillatory movement and provided at its opposite end with a cam follower, a cylindrical cam on said rotating member having a continuous sinuous groove therein providing a cam track for imparting movement positively in two opposite directions to said cam follower, an auxiliary breaker arm mounted at one end on said support extending adjacent to said main breaker arm and positioned beyond the outer surface of said cam, said auxiliary breaker arm having its other end engaging a projecting portion of said cam follower and being provided intermediate the ends thereof with a contact member arranged to engage with and disengage from a contact mounted on said support when the resultant breaker arm structure is oscillated.

18. In a circuit breaking mechanism, the combination with a rotating member, of a stationary support, a' main breaker arm mounted at one end on said support for oscillatory movement and provided at its opposite end with a cam follower, a cylindrical cam on said rotating member having a continuous sinuous groove therein providing a cam track for imparting movement positively in two opposite directions to said cam follower, a resilient auxiliary breaker arm mounted at one end on said support extending adjacent to said main breaker arm and positioned beyond the outer surface of said cam, said auxiliary breaker arm having its other end engaged between spaced apart transverse movement-permitting means on aprojecting portion of said cam follower and being provided intermediate the ends thereof -with a contact member arranged to engage with and disenga e from a contact mounted on said support when the resultant breaker arm structure is oscillated.

LLOYD H. SCOTT. 

